The governor’s Celtic rock band, O’Malley’s March, is booked as the opening act Saturday night for Black 47 at a concert venue in Baltimore.

The New York-based band has played Celtic rock with political overtones for a quarter century and is now on its farewell tour. Saturday’s concert at Sound Stage is billed as Black 47’s “last Baltimore show.”

O’Malley’s semi-retired band, which had its heyday during his run as a Baltimore councilman and mayor, still plays several shows a year and maintains an aging audience.

The governor sings and plays guitar in O’Malley’s March, which is most often booked as a headliner. It has occasionally served as an opening act for kindred musical spirits, including the Saw Doctors, one of the governor’s favorite bands.

Flyer for O’Malley’s show

O’Malley curtailed his band activity after he launched his 2006 campaign for governor. At the time, his advisers argued that the late-night spotlight detracted from his gravitas.

A photo of the governor playing his six-string banjo for passersby at City Dock in Annapolis went viral on Memorial Day. It showed O’Malley wearing a Baltimore Ravens T-shirt, cargo shorts and flip-flops. He appeared to accept tips in his open banjo case.